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TPC Field Cage Progress Report

TPC Field Cage Progress Report. Project Schedule Technical Progress & Prototyping Contractual Matters. Field Cage: Project Schedule. Tests & Prototyping. HV High ionization behavior ( 83 Kr) Temperature stabilization Resistor chain cooling Construction material Compatibility and leaks

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TPC Field Cage Progress Report

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  1. TPC Field Cage Progress Report • Project Schedule • Technical Progress & Prototyping • Contractual Matters Thomas C. Meyer/EP-AIT

  2. Field Cage: Project Schedule Thomas C. Meyer/EP-AIT

  3. Tests & Prototyping • HV • High ionization behavior (83Kr) • Temperature stabilization • Resistor chain cooling • Construction material • Compatibility and leaks • Electrical network • “From strip to central electrode” Thomas C. Meyer/EP-AIT

  4. High Voltage Stability • History: • Field cage was exposed to >16 x expected average charged particle intensityin CERES beam (~ 6000/cm2 s). • Field cage was operated at 1.78 x nominal drift field (~700 V/cm) in pure CO2. • Surface charge phenomena appearing at 60 kV (≥ 400 V/cm). • Insulation gap safe at ≥ 100 kV. Thomas C. Meyer/EP-AIT

  5. High Intensity 83Kr Test • Inject 83Kr with 300 MBq total intensity into field cage (May 2001) • Separate tests for drift and insulation volume. Thomas C. Meyer/EP-AIT

  6. Temperature Stability • History: • Require: DT everywhere ≤ 0.1 ºC • Resistor rod produces 60 W waste heat. • Liquid cooling (H2O) proven very efficient with negligible gradient inside rod but… • H2O unsuitable at HV (dissociation), • Inert liquids dangerous in case of leaks. • New approach: Gas cooling Thomas C. Meyer/EP-AIT

  7. Resistor Rod: Gas Cooling T [ºC] Ambient level z [m] 2.5 • Unlike liquid cooling, DT inside rod always > 0.1 ºC. • --> must insulate rod! • Foam for test • Double wall for ALICE. Thomas C. Meyer/EP-AIT

  8. Gas Cooling: Results Tin = 16 ºC 7 ºC • Inside of rod achieve Dtmin of 7 ºC with 20 m3/h of air: Thomas C. Meyer/EP-AIT

  9. Gas Cooling: Results • Outside of rod achieve required DT of ≤ 0.1 ºC within a few cm from rod: Numbers are given in units of 1/100 ºC; Blue numbers indicate zone around rod with DT < 0.1 ºC Thomas C. Meyer/EP-AIT

  10. Material tests Carbon Fiber DL/L [µm/m] Glass Fiber Kevlar Fiber Macrolon Drying T[ h] Wet Leak test of full-size end plate sector with “CERES” gasket Humidity tests of FC material Thomas C. Meyer/EP-AIT

  11. Voltage Divider: Central Electrode • Focus on “stretched foil” version • High modulus carbon-fiber frames NA48 Example Thomas C. Meyer/EP-AIT

  12. Voltage Divider: Rods & Strips • Ongoing prototyping of all rod types • Resistor rod • HV supply rod • Laser rod • Regular support rod • Verification of strip tension and mounting scheme • Vertical or horizontal? Thomas C. Meyer/EP-AIT

  13. Tooling • Modification of DELPHI support frame • Needed for construction & assembly of FC • Major handling tool for all operations • Finished by end of 2001 Thomas C. Meyer/EP-AIT

  14. Infrastructure: SXL2 • Preparation of dedicated clean area for TPC assembly in LHC interaction region 2: • Finished by December 2001 Clean zone in hall SXL2 Thomas C. Meyer/EP-AIT

  15. Contracting: FC Cylinders • First „Invitation to Tender“ (IT-2726) was launched on schedule in 2000, but... • all offers (4) were above funding level. • Changed scope of tender: • Only production of individual parts (panels & flanges) • Procurement by and assembly at CERN • New tender (IT-2999) sent April 2001 • 6 months delay in schedule Thomas C. Meyer/EP-AIT

  16. Contracting: End Plates • First „Price Inquiry“ was made in 2000. • Lowest bid exceeded funding by large factor. • Try to achieve savings by… • splitting production process (raw material, welding, machining), and • design changes. • New tenders to be launched this month • only if expected savings materialize! • Overall production delay ≥ 6 months. Thomas C. Meyer/EP-AIT

  17. Contracts: Consequences for CERN • Higher manpower load on CERN (TA2) • Higher risks in terms of… • technical failure, • quality control, liability, warrenty! • schedule slippage, • capital loss. • We expect to catch up on the baseline schedule during the internal assembly of the FC (2002/3). Thomas C. Meyer/EP-AIT

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